my experience with driveline lash is multitudinous, and I'll list out the ways:
1. Recent drive-by-wire setups with a sharp transition point. In my 2006 Civic SI, this is particularly pronounced in low-speeds in low-gears and moreso when cold. The car bucks between no throttle and partial throttle, and feels like the drivetrain is transmitting power in a surging fashion. Just a byproduct of poor drive by wire programming, not true driveline lash. (Also occurs in my 2008 Legacy GT, to a far lesser extent).
2. True driveline lash as the gears in the drivetrain rattle slightly under the power pulses of the engine's delivery through the flywheel. This becomes more prevalent in many hard-sprung clutches with single-mass flywheels.
A flywheel acts as a damping force on the engine (it's a heavy mass at the end of the crankshaft). A dual-mass flywheel is actually two masses that are "sprung" together and allow for pulses to be absorbed while still delivering power smoothly through the spinning flywheel (i.e. the flywheel absorbs the surges of pistons delivering their power, rather than transmitting it to the clutch/trans).
A single-mass flywheel does not absorb these surges, so the next step is the clutch. Clutches have "sprung" hubs, where the middle of the clutch usually has ~4 springs that can absorb some of the twisting and then halting motion of the engine's power pulses. If the clutches spring rates are very hard (takes alot of force to compress them), then the power still "pulses" through the transmission.
In order for gears to mesh, they can't be impenetrably tight to each other. As long as power is being delivered, the gears press against each other and the power is seamless. But when "pulses" go through the system, the gears press against each other, relax, press, relax.
And sometimes you get noise. Especially in low gears, when the power pulses come much slower.
The advantage of setups with more noise is, typically, a much crisper power delivery or in some cases (i.e. straight-cut gears) a much stronger way of building the gears.
But sometimes it's also just greater build tolerances between gears and one car will have more noise than another. Kinda like oil consumption on some cars....not a sign anything is wrong, could even be a manufacturer build specification making it happen, but kinda annoys you nonetheless.